Izumo Province (出雲国 Izumo-no-kuni) was an old province of Japan which today consists of the eastern part of Shimane Prefecture. It was sometimes called Unshū (雲州). The province is in the Chūgoku Region.
It was one of the regions of ancient Japan where major political powers arose. A powerful clan of Izumo (Idumo in Old Japanese) constituted an independent polity, but during the 4th century it was absorbed due to the expansion of the state of Yamato, within which it assumed the role of a sacerdotal domain.
Even today, the Izumo Shrine constitutes (as does the Grand Shrine of Ise) one of the most important sacred places of Shinto: it is dedicated to kami, especially to Ōkuninushi (Ō-kuni-nushi-no-mikoto), mythical progeny of Susanoo and all the clans of Izumo. The mythological mother of Japan, the goddess Izanami, is said to be buried on Mt. Hiba, at the border of the old provinces of Izumo and Hōki, near modern-day Yasugi of Shimane Prefecture.
By the Sengoku period, Izumo had lost much of its importance. It was dominated before the Battle of Sekigahara by the Mōri clan, and after Sekigahara, it was an independent fief with a castle town at modern Matsue.
- Shimane Prefecture
- Aika District (秋鹿郡) - merged with Ou and Shimane Districts to become Yatsuka District (八束郡) on April 1, 1896
- Iishi District (飯石郡)
- Izumo District (出雲郡) - merged with Kando and Tatenui Districts to become Hikawa District (簸川郡) on April 1, 1896
- Kando District (神門郡) - merged with Izumo and Tatenui Districts to become Hikawa District on April 1, 1896
- Nita District (仁多郡)
- Nogi District (能義郡) - dissolved
- Ohara District (大原郡) - dissolved
- Ou District (意宇郡) - merged with Aika and Shimane Districts to become Yatsuka District on April 1, 1896
- Shimane District (島根郡) - merged with Aika and Ou Districts to become Yatsuka Districton April 1, 1896
- Tatenui District (楯縫郡) - merged with Izumo and Kando Districts to become Hikawa District on April 1, 1896